Lubricating oil composition containing certain 2:1beta-glycol borate compounds



United States Patent Ofiice Patented June 20, 1961 2,989,470 LUBRICATING OIL COMPOSITION CONTAINING CERTAIN 2:1 B-GLYCOL BORATE COMPOUNDS Samuel M. Darling, Lyndhurst, and Chien-Wei Liao,

Cleveland, Ohio, assignors to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Filed Dec. 30, 1958, Ser. No. 783,669

4 Claims. (Cl. 252 49.6) V

This invention relates to a lubricating oil composition comprising the reaction product of certain fl-alkylenediols with boric acidin the ratio of two moles of the diol to tributes to the deposit but it also converts it from an essentially carbonaceous deposit to one comprising appreciable quantities of lead and lead compounds mixed therewith, such as lead sulfate, and lead oxide. The carbonaceous deposits act as a cementing agent for the lead deposits, and the lead deposits are more diflicult to remove than the carbon deposits. Thus, a deposit of this sort is more tenacious and troublesome than a purely carbonaceous deposit.

The nature of the lead-carbonaceous deposits is such that they are quite difiicult to remove, once they have been built up. They are not attacked by the scavenging agents which are included in the fuel with the tetraethyl lead. Despite the fact that the amount of the deposits eventually levels 01f, after which there, is no appreciable further increase, the presence of the built-up deposits interferes considerably with the operation of the engine, and it would be desirable both'to prevent formation of deposits and to remove them after they have been formed. The disadvantageous effects of these deposits are well discussed in U.S. Patent No. 2,741,548 to Samuel M. Darling, Philip S. Fay and Lorraine S. Szabo.

It has been proposed to attack such deposits by incorporating in the liquid leaded motor fuel an organic boron compound which is soluble in the -fuel. The boron compound is thought to modify the action of the fuel in v v the engine, and to react with the deposits so that the adverse effects due to the deposits are eliminated or markedly reduced.

It is known that the carbonaceous components of the deposits in the engine are built up not only irom the gasoline but also from the oil, which enters the combustion system from the crankcase in various ways. This oil is in the liquid phase in the combustion zone of the engine, whereas the gasoline, of course, is in the vapor phase. However, it is essential that the boron compound be soluble in the medium in which it is introduced into the engine. For use in lubricating oil, the solubility must be quite high, relative to that in gasoline, because more additive is needed in the lubricating oil to obtain an effect. Moreover, the stability of the boron compound against of compound present, and the hydrolysis products must be soluble in the oil as well, since insoluble boron deposits in the crankcase and lubricated parts of the engine might be harmful and certainly would be difficult to remove.

Moreover, the boron compounds incorporated in liquidleaded motor fuels are volatilizable under the combustion zone conditions, and also exist in the vapor phase in the combustion zone. If such organic boron compounds were present in the oil, they would, under the combustion hydrolysis must be high, in view of the larger amounts zone conditions, nonetheless be expected to volatilize.

Compounds having a much higher boiling point are neces sary for use in lubricating oils. Such compounds should also be stable in the presence of moisture. Because of this, 'it hasv not been possible to incorporate-these compounds in the oil. i

It has now been determined, in accordance with the invention, that the reaction products of boric acid with certain B-alkylene glycols in the proportion of one mole boric acid to two moles of the flalkyleneglycols are oilsoluble, more moisture-stable, and have low volatility, provided the glycol has at least sixcarbon atoms up to about twenty carbon atoms. Engines operated with lubricating oils containing such boron compounds have improved performance. The deposits are reduced. The ignition temperature of such engine deposits as remain is increased, therefore repressing surface ignition. It is thought that the boron compounds react with the lead in the deposits forming lead-borate, and that this does not act catalytically to the same extent becausesit has a higher glow point than the lead oxide and lead sulfate usually present in such deposits. These additives are compatible with conventional lubricating oil additives.

The reaction products in accordance with the invention are defined by the following general formula:

where R and R are fi-alkylene radicals having at least six and up to twenty carbon atoms and having the following general formula:

Ti l R2 R4 Ra linking the radical to the group. R and R are both alkyL' R R R and R are selected from the group consisting of hydrogen and alkyl, provided that the total number oi carbon atoms in R and R is at least 6. The R and R and the Ri, R R and R radicals, when alkyl, can be straightchain or branched radicals and have .1 to -17 carbon atoms. Thus, R and R and R R R and R when alkyl, can be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary 'butyl, secondary butyl, amyl, iso-amyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, and octadecyl radicals, taken in suflicient number to meet the requirements of the formula for the total number of six carbon atoms. Thus, when R and R are each methyl, at least one of R R R and R must be at least methyl,

If one B-alkylene glycol is employed, one molecular species is obtainable from the ,B-alkylene glycol and boric acid. If two fi-alkylene glycols are employed, four m0- lecular species are possible, the two borates of each glycol and two to four mixed borates, depending on the symmetry of the glycols.

The extraordinary moisture stability of the compounds of the invention is explained by postulating the existence of a chelated structure, in which the free OH group is attached to the boron by a semicovalent bond, thus:

There is much evidence to support this structure. Since 3 this has not been definitely established, however, the compounds are not shown in this structural arrangement.

Typical of the compounds which come the invention are the following:

It has already been indicated that when one fl-glycol is employed, only one molecular species is formed, and that when a mixture of two is used, two to four molecular species are possible. It will be apparent from the above that more complex mixtures of reaction products can be obtained from mixtures of three and more p-diols. However, all of these are operative in the compositions of the invention.

The borate compounds of the invention are solids or liquids which are stable to moisture. The liquids and the solutions of the compounds in oil remain homoge neous and clear when stored in a moisture-saturated chamber for forty-eight hours at room temperature (25 0.). They are soluble in petroleum lubricating oils at very large concentrations. They are substantially involatile at crankcase temperatures.

These compounds can be prepared by mixing the reactants in the stoichiometric 2:1 molar ratios and heating them above 60 0., up to about 150 0.; on a steam plate or hot plate, with occasional stirring, until the theoretical amount of water is lost. The loss of water is determined by the weight loss of the reaction vessel and contents. AlternativelyQthe reactants can be refluxed in the stoichiometric ratios in dry benzene in a flask provided with a water condenser and a water-collecting trap until the theoretical amount of water has been azeotropically distilled. This permits use of a lower temperature. The water removed isdetermined by thewater in the trap. The benzene then is removed from the reaction mixture by distillation, and the residue vacuum-distilled or recrystallized.

The compounds numbered (2), (4), and (14) above were subjected to screening tests to determine oil solubility, moisture stability and volatility. Oil solubility was observed at a concentration of about 0.1% boron. Moisture stability was studied with both the undiluted liquid additive and an oil solution containing at least the equivalent of 0.1% boron. Samples had to remain visually unchanged with respect to homogeneity and clearness after being stored in a moisture-saturated chamber for forty-eight hours. Volatility was determined by the distillation characteristics of the compounds themselves. The data obtained appears in Table I:

The borate compounds of the invention can be used With any petroleum hydrocarbon oil of lubricating viscosity. The SAE viscosities for lubricating oils range from No. to No. 70. The neutral oils and refined oils, such as the acid-treated and solvent-extracted oils, are equally useful in the compositions of the invention. The oils may be blended from suitable bright stocks and finished neutral or refined oils of light and heavy viscosities. It is impossible here to give a complete description of the various methods used in the preparation of lubricating oils, but reference is made to the text by Georgi entitled Motor Oils and Engine Lubrication, published by Reinhold Publishing Corporation, New York (1950), chapter V, wherein the various types of lubricating oils are discussed fully. Any of the oils mentioned therein can be employed in the compositions of the invention.

Relatively large amounts of the organic borate compounds of the invention, in oils as compared to the amounts required in gasoline, are needed to give an improvement in engine performance. All proportions of the compounds are based on the amount of boron in the compound as a percent of the total oil composition, since it is the boron that is the active component in removing the deposit. At least 0.05% is the minimum. Use of amounts in excess of 0.5% usually cannot be justified economically, and excessive amounts may lower the viscosity index.

The composition of the invention is prepared simply by mixing the boron compound with the oil at room temperature. The boron compound is soluble in the oil, and dissolves therein either instantaneously or after a short time. No solvents are required.

The following examples represent in the opinion of the inventors the best embodiments of their invention:

Examples 1 to 3 Three lubricating oil compositions were prepared using a lubricating oil blend of 67% solvent-extracted neutral oil, 300 SSU at 100 F. and 33% of a solvent-extracted 6 bright stock 78 SSU at 210 F. To' the oil was added 2% of the following borate compounds:

EXAMPLE 1 om-o crave-02H. n-o-om-o-crrrou EXAMPLE 2 1 Cr s OH; CH;

When the above oils were used in the crankcase of an internal combustion engine operating for a period of over seventy-two hours on non boron-containing gasoline and the engine was then dismantled, the deposits in the combustion chamber were found to contain boron with the attendant advantages of the same in the deposit as discussed earlier.

The compositions were subject to the Falex E.P. test, run by the standard procedure, where the load on the bearing was increased automatically and the pressure re ported was that registered at failure. The wear tests were run on the same equipment using a constant pressure on the bearing.

The data showed that the oil of the invention containing the boron compound tolerated higher pressure and produced less wear than either the corresponding blend without boron or the base oil alone, thereby indicating that there would be no adverse effect by the use in crankcases of engines.

We claim:

1. Petroleum lubricating oil having dissolved therein a moisture-stable organic boron compound having the formula:

where R and R are B-alkylene groups having from six to twenty carbon atoms having the structure:

R1 R: R5

it. is. l.

the free valences being attached to oxygen, R and R both being alkyl and R R R and R being selected from the group consisting of hydrogen and alkyl, the amount of said compound based on the weight of the lubricating oil being equivalent to from 0.1 to 0.5% by weight of boron.

2. Lubricating oil in accordance with claim 1 in which the boron compound is:

3. Lubricating oil in accordance with claim 1 in which the boron compound is:

' 4. Lubricating oil in accordanccwith claim 1 in which the boron compound is:

C Hr-O References Cited in the file of this patent 8 Darling June 7, 1955 Darling et a1. Apt. 10, 1956 Thomas et a1. June 11, 1957 Garner June 17, 1958 Irish et a1. Dec. 3Q, 1958 FOREIGN PATENTS Great Britain -t. Ian. 26, 1955 

1. PETROLEUM LUBRICATING OIL HAVING DISSOLVED THEREIN A MOISTURE-STABLE ORGANIC BORON COMPOUND HAVING THE FORMULA: 